1. Field of the Invention
The invention relates to new compositions of matter which can be utilized as colorant compounds. In particular applications, the invention pertains to phase change ink formulations. In other particular applications, the invention pertains to methods of printing.
2. Description of Relevant Art
The present invention encompasses new colorant compounds and methodology for incorporating such compounds into phase change inks. Phase change inks are compositions which are in a solid phase at ambient temperature, but which exist in a liquid phase at an elevated operating temperature of an ink jet printing device. At the jet operating temperature, droplets of liquid ink are ejected from the printing device. When the ink droplets contact the surface of a printing media, they solidify to form a printed pattern. Phase change ink methodology is described generally in U.S. Pat. Nos. 4,889,560; 5,372,852 and 5,827,918.
Phase change inks generally comprise a waxy organic compound (typically a tetra-amide material), a tackifier, and a viscosity modifying agent as primary components. An exemplary viscosity modifying agent is stearylstearamide, which can be provided to a concentration of less than or equal to about 60% (by weight). An exemplary tackifier is KE-100 Resin, an ester of tetrahydroabietic acid and glycerol, which is available from Arakawa Chemical Industries Ltd. Tackifiers are typically provided to a concentration of less than or equal to about 30% (by weight). Exemplary tetra-amide compounds can be formed by reacting ethylene diamine with a dimer acid and an appropriate fatty acid.
In addition to the above-described primary components, phase change inks can comprise a number of secondary components, such as, for example, colorants (for example, dyes), plasticizers, and antioxidants, as described in, for example, U.S. Pat. Nos. 4,889,560 and 5,372,852.
A definition which will be adopted in this disclosure and the claims that follow will be to refer to a phase change ink composition as comprising a colorant and a carrier. The term xe2x80x9ccarrierxe2x80x9d is to be understood to comprise everything in the phase change ink composition besides the colorant. In phase change ink compositions comprising more than one colorant, the carrier will include everything except a particular colorant of interest, and can, therefore, comprise colorants other than that which is of interest.
A difficulty associated with phase change inks can be in solubilizing colorants. The colorants generally comprise polar functional groups, and accordingly are insoluble in an organic carrier of a phase change ink composition. Accordingly, it is desirable to develop new colorants having improved solubility in phase change ink carrier compositions.
An exemplary prior art colorant compound is C.I. Solvent Red 172, which is shown below as formula 1. 
Such colorant manifests a magenta color that could be useful in phase change inks. However, C.I. Solvent Red 172 has less than satisfactory solubility in present phase change ink carrier compositions. Accordingly, it would be desirable to form a composition having chromophoric properties similar to C.I. Solvent Red 172, but with improved solubility in phase change ink carrier compositions.
In one aspect, the invention encompasses compounds having the formula 2: 
wherein at least one Q1, Q2, Q3 and Q4 is a halogen atom and any of Q1, Q2, Q3 and Q4 which is not a halogen atom is a hydrogen atom; and wherein R comprises at least two carbon atoms. The invention further encompasses inclusion of such compounds into phase change ink carrier compositions, as well as printing methods utilizing such compounds.
In another aspect, the invention encompasses compounds having the formula 3: 
wherein X and Y are halogen atoms and can be the same or different than one another, and wherein R comprises at least two carbon atoms. The invention further comprises inclusion of such compounds in phase change ink compositions, and printing methods utilizing such compounds.
In yet another aspect, the invention encompasses compounds having the formula 4: 
wherein X is a halogen atom, and wherein R comprises at least two carbon atoms. The invention further encompasses inclusion of such compounds into phase change ink carrier compositions, as well as printing methods utilizing such compounds.